Characterization and lithographic parameters extraction for the modified resists

The modification of the i-line resist structure after spiking with various amount of poly(4-vinylphenol) polymer is characterized by the spectra of ultraviolet visible (UV-VIS) and gel permeation chromatography (GPC). The chemical structure of photoactive compound is found to be unchanged after modification, while slight change in the polymer chain is observed. The resist layer coated onto the wafer is characterized by various methods including n&k analyzer, Nanospec, Fourier transform infrared red (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to fully evaluate the film properties in terms of porosity, thickness, vibrational spectrum, and thermal stability. Our thermal analysis results show that the resists are mainly decomposed in three stages. The photoactive compound (PAC) is found to decompose during the first stage, while the polymer decomposes during the latter stages. The resist exposure parameters, namely, A, B and C at 365 nm are determined by the absorbance measurement. The extracted parameters are further used in the resist profile simulation by PROLITH/2. It is shown that the spiking of poly(4-vinylphenol) polymer into the resist can improve the resolution and linearity for dense lines. In addition, the swing effects can be reduced by up to 35 and 31% for dense and isolated lines apter resist modification, respectively.